The present invention pertains to fire extinguishers with alarms, which are automatically activated by a fire so as to discharge fire extinguishing material and simultaneously raise an alarm to notify persons or systems of the existence of the fire. Such devices are particularly suitable for use with wastebaskets or other receptacles for flammable waste material, and for computer cabinets, though the present invention is not limited in application to such devices.
Earlier patents describe a number of fire extinguisher devices in which the heat from a fire automatically effects release of fire extinguisher material through the melting of a seal, fuse or plug, or by the rupturing of a diaphragm due to pressure of fire extinguisher material caused by the heat of the fire. In some of these devices, the escaping fluid passes through a whistle, tapered aperture or horn, so as to sound an audible alarm.
The patent of Linsalato (U.S. Pat. No. 3,907,037) discloses a disposable fire extinguisher in which pressurized fire extinguisher material is conveyed from a container through discharge tubes having orifices with caps normally held in place by fusible alloy seals. Upon exposure to heat from the fire the fusible alloy seals melt, allowing the pressurized fire extinguisher fluid to force the caps off the ends of the discharge tubes, whereupon the fire extinguisher fluid is discharged onto the fire. Col 2, lines 12-47; Col 3, lines 25-49; FIGS. 2, 3, 5, ref. Nos. 20, 54, 42, 44, 38, 40, 70 and 72. The patent states that previous fire extinguishers have used a meltable plug, fusible solder around a cover, or a band of fusible material to cause discharge of pressurized fire extinguisher fluid. Col. 1, lines 8-15.
The patent of Berti et al. (U.S. Pat. No. 3,536,139) discloses a fire extinguisher for a trash container in which release of fire extinguisher fluid is automatically effected by the melting of a fuse which normally holds one end of a lever arm under tension in a position such that the other end of the lever arm holds a valve stem in the valve closed position. When the fuse melts, the lever arms and valve stem are freed, allowing the valve to open under the pressure of the fire extinguisher fluid, so as to release the fluid to extinguish the fire. Col 2, lines 49-68; col 3, lines 16-36; FIGS. 5, 6, ref. Nos. 20, 22, 24, 40, 44, 36, 38, 12.
The patent of LeDay (U.S. Pat. No. 4,034,813) discloses a combined fire extinguisher and audible alarm in which pressurized fire extinguisher fluid is released into a waste receptacle when heat from the fire melts a seal, releasing a trigger, allowing the pressurized fluid to open a valve and exit a nozzle onto the fire. The fluid exits through tapered aperatures, producing an audible alarm. Col 1, lines 44-63; col 3, lines 27-68; FIG. 3, ref. Nos. 64, 62, 84, 84a, 86, 78, 76, 76a, 76b.
The patent of Hayes (U.S. Pat. No. 3,520,368) discloses an automatic fire alarm in which a container of pressurized fluid is exposed to heat from a fire, causing increased fluid pressure to rupture a diaphragm, allowing the fluid to escape through a whistle, thus sounding an alarm. Col 3, lines 7-36; FIG. 1, ref. Nos. 10, 11, 12a, 14 and 15.
Of course it is possible, in lieu of the means disclosed in LeDay and Hayes, to allow pressurized escaping gas to sound an alarm by having some portion of the gas activate a conventional gas-operated horn, such as the horns disclosed in the patents of Pappas (U.S. Pat. No. 3,757,731) or Swanson (U.S. Pat. No. 3,670,690).
One significant problem encountered in a device which simultaneously releases fire extinguisher fluid onto a fire, and also uses the escaping fluid to sound an alarm by passing through an appropriate whistle or horn, is a problem of timing. Obviously, it is desirable that the fire extinguisher fluid be released onto the fire fairly quickly, so that the fire can hopefully be overwhelmed and extinguished at its inception. But, on the other hand, it is desirable to have an audible alarm which will continue to sound for a longer time period, since a person may not be within earshot at the moment the alarm first sounds.
Another problem with such a device is the liquid versus gas phase problem concerning the fire extinguisher material and audio alarm activating material. Applicants' tests indicate that the use of fire extinguisher material such as Halon 1211 in liquid form is more effective for fire extinguishing than use of the gaseous form. Yet the use of gaseous material is preferable for purposes of operating an audible alarm, such as a conventional vibrating diaphragm gas horn.
Applicants' invention deals with these problems by providing 2 reservoirs, one containing fire extinguisher fluid in liquid form for fire extinguishing, and the other containing material at least partially in gaseous form, for operation of the gas horn, and by providing a mechanism which automatically causes gas from the second reservoir to flow through the gas horn when fire extinguisher material is released onto the fire from the first reservoir.
Another problem with conventional extinguisher-alarm devices such as those described above is that the fire extinguisher material may be lost due to a leak. If, for example, the heat sensing element and discharge tube of the device are located within or just above a waste receptable, such a leak may result from damage to the discharge tube occurring when some object is thrown into the waste receptacle, striking the discharge tube. It is desirable that there be a means of automatically calling attention to any loss of pressure of the fire extinguisher material. Applicants' invention also deals with this problem, since, as described below, gas will be released from the second reservoir through the gas horn if pressure is lost in the first reservoir due to a leak, as well as when pressure is lost because the fire extinguisher material is discharged onto a fire.